MX1 and systemic sclerosis: Individual levels of DNA damage in SSc PBMCs correlated significantly with the corresponding mRNA expression of type I interferon–induced genes (IFIT1, IFI44 and MX1, r=0.419-0.490) as well as with corresponding skin involvement extent by modified Rodnan skin score (r=0.481). In conclusion, defective DDR/R may exert a fuel-on-fire effect on type I interferon pathway activation and contribute to tissue fibrosis in SSc.